Secretory processes in several cell types are currently under investigation. Cell dissociation and short term culture (up to 1 month) methods have been established for rat exorbital lacrimal, parotid and pancreatic acinar cells. These cultures are being used to study various aspects of the secretory process. Initial emphasis is being placed on morphological, cytochemical and biochemical characterization of the cultured cells. Additionally, uptake of horseradish peroxidase and internalization of 125I labeled cell membrane are being investigated, in vivo and in vitro. The events involved in matrix deposition by cultured odontoblasts, and melanosome formation in cultured neural crest cells, are also being studied.